Authorities at Ghezel Hesar Prison in Karaj, Alborz Province, executed prisoner Mohammad Reza Ghorbani on 28 January on drug-related charges.
Ghorbani was transferred to solitary confinement for execution on 27 January along with another prisoner, Hossein Havasi.
Havasi was returned to the general ward several hours later, but Ghorbani was executed the following morning.
Ghorbani, from Abdanan in Ilam Province, was arrested about five years ago on drug trafficking charges.